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arXiv · 1907.09330

Bound states in the continuum in symmetric and asymmetric photonic crystal slabs

Anton I. Ovcharenko·Cédric Blanchard·Jean-Paul Hugonin·Christophe Sauvan
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Abstract

We develop a semi-analytical model to describe bound states in the continuum (BICs) in photonic crystal slabs. We model leaky modes supported by photonic crystal slabs as a transverse Fabry-Perot resonance composed of a few propagative Bloch waves bouncing back and forth vertically inside the slab. This multimode Fabry-Perot model accurately predicts the existence of BICs and their positions in the parameter space. We show that, regardless of the slab thickness, BICs cannot exist below a cut-off frequency, which is related to the existence of the second-order Bloch wave in the photonic crystal. Thanks to the semi-analyticity of the model, we investigate the dynamics of BICs with the slab thickness in symmetric and asymmetric photonic crystal slabs. We evidence that the symmetry-protected BICs that exist in symmetric structures at the {\Gamma}-point of the dispersion diagram can still exist when the horizontal mirror symmetry is broken, but only for particular values of the slab thickness.

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Anton I. Ovcharenko, Cédric Blanchard, Jean-Paul Hugonin, Christophe Sauvan. 2019-07-22. Bound states in the continuum in symmetric and asymmetric photonic crystal slabs. https://doi.org/10.1103/physrevb.101.155303

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